Abstract: In order to solve the problems in the power industry, such as the backward technology of substation security detection system, the inability to realize centralized management and control, the high rate of false alarm and the inability to meet the requirements of all-weather protection, in this paper, a new intelligent early warning system for fence based on Sagnac effect technology is adopted, and the basic structure model of intelligent early warning system for fence based on fence is constructed according to the general requirements of modern perimeter and electric power industry, according to the physical layer, the acquisition layer, the algorithm layer and the application layer, the key technologies involved in each layer are analyzed, the feasibility of the model to realize the functions of intelligent location, intelligent perception, distributed monitoring, anti-interference ability, response time and so on is demonstrated.Finally, according to the structural model, the preliminary design scheme of the fence intelligent early-warning security system is proposed.This paper puts forward some measures, such as no active device signal in the open air, the linkage of intrusion alarm and video surveillance, and user-customized grading alarm, which can effectively solve the problems of poor anti-interference ability and high false alarm rate, and improve the security level of our country.